Preparation of vinyl sulfones



action of mercaptans with acetylene under presrne aa July 5, 1949 PREPARATION OF VINYL SULFONES Dwight L. Schoene, Naugatuck, (lonn'. asslgnor to United States Rubber Company, New York, N. 1., a corporation of New Jersey No Drawing. Application January 10, 1947,

Serial No. 721,479.

'10 claims. 1 This invention relates to an improved method of preparation of vinyl sulfones.

Vinyl sulfones are known to be extremely reactive chemicals of potential value as intermediates in the production of a number of valuable chemicals. However, difficulties in preparation have limited their use. The recorded syntheses to date have involved toxic intermediates or have made use of reactants which are potentially explosive. One procedure involves the oxidation of the highly obnoxious beta-chloroethyl sulfides followed by dehydrochlorination. Another procedure involves the oxidation of vinyl sulfides which in turn are derived from the resure, Such reactions require considerable precautions in order to avoid the explosions which a 2 (beta-acetoxyethyl) sulfone yield vinyl sulfone on pyrolysis. By varying the B group of the betahydroxyethyl or beta-alkylcarbonyl-oxethyl sulfone, the following are representative of the vinyl 1 sulfones 'producible by pyrolysis: vinyl sulfone,

' methyl vinyl sulfone, ethyl vinyl sulfone, n-prooften occur with acetylene under pressure. My

new method of synthesis eliminates these dis-' advantages and permits the preparation of vinyl sulfones with a minimum of hazard.

I have found that beta-hydroxyethyl sulfones may. be converted to the corresponding vinyl compounds by subjecting them to pyrolytic conditions. In carrying out the new synthesis, the beta-hydroxyethyl sulfones, or the carboxylic acid esters thereof, such as the alkanoic esters, viz. the beta-alkylcarboxyl-oxyethyl sulfones, having the general formula where R is an alkyl, cycloalkyl, alkenyl, aryl, or aralkyl radical or the group CHz-CHa-X and where X is hydrogen or an alkyl carbonyl group, are introduced into a heated chamber, preferably containing a contact agent, which may or may not have a catalytic action. The heated chamber is preferably so equipped that the pyrolysate may be withdrawn at about the same rate as the addition. This treatment converts at least a portion of the starting sulfone to RSO :CH=CH2 and HOX which are withdrawn along with any unreacted starting material. ,The vinyl sulfone and the HOX (water or organic acid) portion are separated from the parent compound by distillation or crystallization and the unreacted starting material is recirculated for further Dye rolysis. As illustrative, when R. is ethyland X is hydrogen, as in ethyl-beta-hydroxyethyl sulfone,"

"pyrolysis gives ethyl vinyl sulione and water.

When R is methyl and X is as alkyl carbonyl group, for exampleacetyl as in methyl-beta-acetoxyethel sulfone, pyrolysis gives methyl vinyl sulione and the alkanoic acid, acetic acid. Simpyl vinyl sulfone, isoprop'yl vinyl sulfone, allyl vinyl sulfone, n-butyl vinyl sulfone, 2-butenyl.

vinyl sulfone, secondary butyl vinyl sulfone, tbutyl vinyl sulfone, n-amyl vinyl sulfone, isoamyl vinyl sulfone, cyclohexal vinyl s'ulfone, octyl vinyl sulfone, dodecyl vinyl sulfone, octadecenyl vinyl sulfone, octadecyl vinyl sulfone, phenyl vinyl sulfone. D-chlorophenyl vinyl sulfone, p-tolyl vinyl sulfone, naphthyl vinyl sulfone, phenethyl vinyl sulfone, benzyl vinyl sulfone.

In general, I prefer to conduct the pyrolysis at reduced pressures of the order of 1 to mm. of mercury since this provides a more convenient means of removing the pyrolysates. Atmospheric or superatmospheric pressures may be employed as well, if desired, at a somewhat greater loss due to carbonization. Depending upon the contact agent used, pyrolysis temperaturesmay vary from about C. to about 600 C. In the pres ence of a contact agentsuch as alumina which is an effective catalyst, p olysis occurs at temperatures as low as about 50 C. although the reaction is more rapid and complete at a temperature of about 200 C. More efflcient use of the catalyst is obtained by preheating the sulfone. With a relatively inert material such as glass in the pyrolysis chamber, temperatures of 400-600 C. are satisfactory with the higher temperatures giving faster rates. Many other catalysts or heat transfer agents may be used such as silica, carborundum, aluminum and other metals, graphite, quartz chips, titania and the like.

The following examples are illustrative of the invention:

Example I A three-neck, round bottom, 500 ml. flask is partially immersed in a metal bath maintained at 240 C. and charged with 150 g. of 4-8 mesh alumina. The flask is equipped with a dropping funnel, an inlet tube for nitrogen and a lagged 10 x 0.5 inch Vigreaux type column. The system is evacuated to a pressure of 20 mm. mercury and, after preheating the alumina for an hour, 200 g. of beta-acetoxyethyl methyl sulfone is added dropwise over a period of two hours. A slow stream of nitrogen is passed through the system throughout the addition. Shortly after the addition is started the pyrolysate beginsto distill ilarly, v bls(beta-hydroxyethyl) sulfone or bis 55 through the short column and is collected in an is added over a period of seven hours. alumina darkens somewhat, especially at the top ice-cooled condenser. At the end 01' the addition,

' heat and vacuum are maintained for thirty minutes to insure removal of the product from the alumina. The yield of yellow pyrolysate is 164 g., a recovery of 82 percent.

The pyrolysate is distilledat reduced pressure through a short column; The acetic acid fraction is discarded and 93.5 g. of substantially pure methyl vinyl sulfone is collected at 114 C./16 mm. as a colorless oil. Refractive index, n ns 1.4589. This corresponds to a yield of 72 percent of theory. The residue consisting chiefly 01 um reacted starting material totals 15 g.

Example II Using the technique of Example I. 150 g. of beta-hydroxyethyl methyl sulfone is pyrolyzed by dropping it at a rate of 70 drops per minute onto 50 g. of 4-8 mesh alumina maintained at a bath temperature of 250-290 C. The vapor temperature rises to about 97 C./20 mm. and slowly increases to about 170 C./20 mm. which indicates that some of the starting material is distilling along with the pyrolysate. An additional 50 g. of alumina is added and the pyrolysis is continued. The vapor-temperature now remains at about 100 C./20 mm. At the end of the reaction, 95 g. of pale yellow oil is collected in the air cooled trap and an additional 25 g. of pyrolysate, largely water, is collected in the dry ice cooled trap. The loss amounts to 30 g.

The oil is distilled through a x 0.5 inch column packed with $4 inch saddles. A small amount of yellow forerun boiling up to 108 C./12 mm. is discarded and themain fraction is taken at .94 C./7 mm.- It consists of 71 g. of methyl vinyl sulfone which corresponds asvgsos to a yield of 55 percent. The dark, fluid residue alumina, and heated under vacuum for 1.5 hours at 300 C. The tube and wrapping are inserted into a slightly'larger tube which serves to prevent heat-loss. The temperature is then reduced to 260 C. and the dropwise addition of beta-hydroxyethyl methyl sulfone (94 percent purity) is started. The initial pressure is20 mm. The first pyrolysate is colorless but soon becomes dark brown. The temperature, measured by a thermocouple in an indentation in the pyrolysis tube, is reduced to 230 C. at a pressure of 10 mm. and the pyrolysate becomes light yellow. A still lighter product is obtained at 200-220 C. and the balance of the run is carried out at this temperature. A total of 502 g. of the hydroxy sulfone The where it comes in contact with the liquid hydroxy sulfone, but no appreciable carbonization is observed. The final pyrolysate, collected in an ice cooled receiver, weighs 467 g. which corresponds to a recovery of 92 percent. Distillation yields 306 g. of substantially pure methyl vinyl sulfone leaving a residue of '70 g. which is largely unreaeted starting material. Thus the conversion is 74 percent and the yield, corrected for the unreacted residue, is 90 percent of theory.

Example IV Using the technique of Example III, 310 g. of crude beta-acetoxyethyl methyl sulfone mixed with 50 ml. of glacial acetic acid (to keep the low melting sulfone from crystallizing in the dropping funnel) is pyrolyzed' at 200 C./l5 mm. Fine alumina dust in the 4-8 mesh alumina used makes a slow addition rate necessary to prevent excessive flooding in the column and some seven hours are required to complete the addition. The: pyrolysate, recovered as a light yellow oil. totals. 316 g. (88 percent). Distillation through ashortv packed column yields 134.5 g. 0! methyl vinyli sulfone boiling at 100-101 C./9 min, a 1.4504."

Example V Using the technique of Example 111, 12 f; 'm' y t yl ethyl sulfone is pyrolyzed t 240-260 C./10 mm. A period or four hoursis required for the addition. The first pyrolysate is colorless but becomes yellow as the run progresses;-

Some carbonization is observed on the walls 0!;

yellow forerun. There is very little residue. The;

total yield based on the two fractions amounts to. 77 percent of theory.

Example VI Using the technique oi Example I, 63.5 g. of bis- (beta-acetoxyethyl) sulfone is pyrolyzed using 100 g. of alumina at a bath temperature of 320 0..

The dropping rate is 60 per minute and the pres-,.

sure is maintained at 80-100 mm. An appreciable.

quantity of gas is formed which does not con-; dense in the water cooled condenser while 42 g.i I

of yellow liquid pyrolysate is collected. Distilla-i tion of the product gives 19 g. of acetic acid and 16 g. of slightly yellow vinyl sulfone boiling at." 71-72" C./3 mm., n 1.4750. The residue weighs 7 g. and includes both starting material and the half pyrolysate. Redistillation of the vinyl sulfone gives 14.5 g. of colorless vinyl sulfone boiling at 65 C./2 mm. 11 1.4740. The material has both lachrymatory and vesicant action.

Example VII Using the technique of Example I, 200 g. of crude bis-(beta-acetoxyethyl) sulfone is pyrolyzed on g. of 4-8 mesh alumina. The dropping rate is 60 per minute and the initial bath temperature is 330 C. at a pressure of 80- 100 mm. This results in the .formation of much non-condensable gas along with the liquid pyrolysate. When the temperature is reduced to 280 C. and the pressure to 10-40 mm., the no! condensable gas is no longer formed and a clear yellow pyrolysate distills at a vapor temperature of -140 C. The final product weighs 146 g. ('73 percent). Distillation or the product gives the following fractions:

1. '70 g. boiling up to 50 C./2 mm. and consisting chiefly of acetic acid.

2. 37 g. of crude vinyl sulfone boiling at 6 C./2 mm.

3. 34 g. of crude 'beta-acetoxyethyl vinyl sultone boiling at -40 C./2 mm.

4. 6 g. of dark residue consisting chiefly 0! starting material.

, droxyethyl) -sulfone.

anasoe l This shows that the yield of the half-pyrolysate can be increased by removing it rapidly from the pyrolysis chamber, i. e. by the use'of low pressures which allows entrainment oi the betaacetoxyethyl vinyl sulione in the more volatile acetic acid and vinyl sulione.

' Example vm An 18 mm. inside diameter Pyrex tube is mounted vertically and packed to a depth of 25 cm; with 6 x 6 mm.pieces of Pyrex tubing. The

tube is heated to about 540 C. by means oi. a

. sate is condensed in a water-cooled trap at the bottom of the tube and weighs 41 g. On standing it darkens appreciabIyL Distillation under reduced pressure gives 18.5 g. of acetic acid and 12.4 g. of substantially pure vinyl sulione.

. Example IX .low solid, indicating decomposition. The temperature is reduced to 200 C. and the pyrolysate remains almost colorless and only partially crys-i talline. The bulk of the crystalline material, thioxane-Ll-dioxide, remains in the condenser while the liquid vinyl sulfone collects in the receiver. About onehour is required for the pyrolysis plus another hour during which the tube isheated under vacuum to remove the pyrolysate. The final product contains 11 g. of water, 10 g. of crude vinyl sulfone, an" 1.4838, and 8 g. of thioxane-1,1-dioxide. Losses thus are 11 g;

This example shows that two products are possible from the direct pyrolysis of bis-(beta-hy- Thioxane-1,1-dioxide is formed by the elimination of one molecule of water while vinyl sulfone results from the removal of two molecules of water. The thioxane derivative is not. formed when the acetate of bis-(betahydroxyethyl) -sulfone is pyrolyzed. (Examples VI, VII and V111.)

Example X Using the technique of Example III, 223 g. of beta-hydroxyethyl isobutyl sulfone is pyrolyzed at a temperature of 200-220 C./10-15 mm. The addition rate is 50 g. per hour. The pale yellow pyrolysate, comprising an aqueous and an isobutyl sulione layer, totals 179 g. (81 percent).

"Distillation through a short packed column gives 146 g. (74 percent of theory) of isobutyl vinyl sulfone boiling at 83-90 C./1 mm. and leaves a 10 g. residue. Redistillation gives 128 g. of substantially pure isobutyl vinyl sulfone boiling at 86 C./1 mm., an 1.4610.

Example XI coil'o'f resistance wire. A slow stream of nitro- I 0./1 no" 1.4622,' and 20 g. of asli ghtly less pure i'raction boilingat the same temperature but with a slight yellow color, no" 1.4828. The residue totaled 18 g. The conversion is thus 88 percent and the yield, correcting for the residue,

is 93.5 percent.

Example XII Using the technique 0! Example 111, '10 g. of

molten beta-hydroxyethyl phenethyl sulione is pyrolyzed at a temperature 01250 C. using a- .pressure of 245' mm. The addition rate is 50 'g. per hour. The pyrolysate is dark and semi-crystalline. It is dissolved in chloroform, dried over anhydrous magnesium sulfate and the crystals or phenethyl vinyl sulione precipitated by the addition 01 petroleum ether (B. I. -80 C.). The crystals weigh 21 g., are substantially white'and melt at 72 C. Recrystallization from benzenepetroleum ether raises the melting point to 73 C.

- Example xm 7 Using the technique of Example III, g. of crude beta-hydroxyethyl tolyl sulione is pyrolyzed at a temperature of 200-230 C. using a pressure of 2 mm. The addition requires one hour. The bulk or the pyrolysate crystallizes at the cool end of the pyrolysis tube and is washed out with benzene. The water formed is not condensed. Evaporation oi the benzene solution gives 13 g. of pyrolysate from which 7 g. of p-tolyl vinyl suifone is recovered by recrystallization from chloroiorm-petroleum ether. The purified crystals melt to a colorless oil at 57 C.

In view of the many changes and modifications that may be made without departing from the principles underlying the invention, reference should be made to the appended claims for an understanding of the scope of the protection 81-. forded the invention.

Having thus described my invention, what I claim and desire to protect by Letters Patent is:

1. The method of preparing vinyl sulfones which comprises subjecting material from the group consisting of beta-hydroxyethyl sulfones and alkanoie esters thereof, to heat decomposition 1 between 150 C. and 600 C.

packed column gives 256 g. or colorless, substantially pure u-butyl vinyl s'ulione boiling at -83 20 150' C. and 600 C.

2. The method of preparing vinyl sulfones which comprises subjecting material from the group consisting of beta-hydroxyethyl sulfones and alkanoic esters thereof, to heat decomposition between 150 C. and 600 C. and between 1 and mm. of mercury pressure.

3. The method of preparing vinyl sulfones which comprises subjecting a beta-hydroxyethyl sulione to heat decomposition between C.

and 600 C. 4 I

4. The method of preparing vinyl sulfones which comprises subjecting a beta-hydroxyethyl sulione to heat decomposition between 150 C. and 600 C., and between 1 and 100 mm. of mercury pressure 5. The method of preparing vinyl sulfones which comprises subjecting an alkanoic ester of a. beta-hydroxyethyl sulfone to heat decomposition between 150 C. and 600 C.

6. The method of preparing vinyl sulfones which comprises subjecting an alkanoic ester of a beta-hydroxyethyl sultone to heat decomposition between 150 C. and 600 C.; and between 1 and 100 mm. of mercury pressure.

'7. The method of preparing vinyl sulione which comprises subjecting bis(beta-hydroxyethyl) suiione to heat decomposition between c 7 8 8. The method of preparing vinyl suli'one ethyl) sultone to heat decomposition between which C pr l flnfl. e -hydroxr- 7 150 C. and 600 C and between 1 and 100: mm.

ethyl) sulfone to heat decomposition between 150 of mercury pressure. 1

C. and 600" 0., and between 1 and 100 mm. of 7 DWIGHTL. BCHOENE. mercury pressure. 5

9. The method of preparing vinyl sulione REFERENCES CITED which comprises subjecting bmbeta'acetom' The following references are of record in the ethyl) sulfone to heat decomposition between 150 C- and Q file of this patent.

10 The method of preparmg vinyl sulfona 3o Chem. Abs. (1930) 242 4257 and 4258. which comprises subjecting bls(beta:acetoxy- 

